It is known that the construction, by a flight management system of the FMS (Flight Management System) type of an aircraft, of departure or arrival procedures at airports necessitates, in particular cases, the definition of unspecified termination segments. Such an unspecified termination segment is principally used for air to traffic control requirements.
When a procedure containing an unspecified termination segment is defined in the flight management system during the definition of a flight plan, this segment is linked to the other segments by defining a discontinuity between its start and the start of the following segment.
In the context of the present invention, “following segment” is understood to mean the first segment of the flight plan which follows the unspecified termination segment in the direction of flight along the flight plan.
Consequently, for an unspecified termination segment, the start point of and the end point, namely the start of the following segment, of this segment are known, but not its geometric evolution between these two points.
For an arrival procedure for example, aircraft arriving at the start of the unspecified termination segment will fly according to a particular heading or a particular route. The air traffic control services, as a function of the positions of other aircraft, will then guide them according to successive headings until they reach the following segment.
After the definition of a flight plan, the flight management system of an aircraft can calculate elements of prediction to destination such as the distance to destination, the fuel necessary, the descent profile, . . . In order to calculate these prediction elements, when the flight plan contains an unspecified termination segment, an assumption must be made regarding the distance flown for this segment.